profiling: allow loading profiling extension before everything else 6d642ecf1a89 makes profiler start early without loading extensions. That makes it impossible for an extension to add customized profilers. This patch adds a special case: if a profiler is not found but an extension with the same name could be loaded, load that extension first, and expect it to have a "profile" contextmanager method. This allows customized profilers and extension setup time is still profiled.

--- a/mercurial/extensions.py	Mon May 22 00:51:56 2017 -0700
+++ b/mercurial/extensions.py	Mon May 22 01:17:49 2017 -0700
@@ -181,7 +181,7 @@
 
 def loadall(ui, whitelist=None):
     result = ui.configitems("extensions")
-    if whitelist:
+    if whitelist is not None:
         result = [(k, v) for (k, v) in result if k in whitelist]
     newindex = len(_order)
     for (name, path) in result: